We present a transparent touch sensor based on single layers of graphene that works under a gentle touch. Using the flexible characteristics of graphene, a touching event and a vertical force are measured by a change in the channel conductance. In contrast to the previous graphene gauge sensors, this is an alternative scheme that responds to a vertical force using the contacting properties of two isolated and patterned single graphene layers. This sensor responded to pressures ranging from 1 to 14 kPa, corresponding to the lowest human perception. In addition, we outline the processing methods for handling single layers of graphene for the integration of devices on transparent and flexible substrates.

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The electromechanical properties of single-layer graphene have inspired specific application to force sensors, sinceit is capable of sensing within the range of human pressure perception. In this study, we present a pressure sensor for vertical force that is flexible and transparent by introducing a single graphene layer on a polyethylene naphthalate substrate. This substrate is commonly used as a force absorber in sensors. By employing it with a pressure amplifying structure, the performance of the sensor shows a reliable resistance change of 0.15% per 1 kPa of applied vertical pressure. Detection for the motion of the finger joint and touching are demonstrated with the sensor equipped on the human body.